It has been well known for years to utilize waste oil in burner and heater systems. For a good description of the problems unique to the preheating and burning of waste oil, see U.S. Pat. No. 4,877,395 issued to Schubach on Oct. 31, 1989. In the typical waste oil burner system, the waste oil is contained in and pumped from a reservoir, and thereafter delivered to a nozzle. The aperture in the nozzle atomizes the waste oil in a spray configuration. The atomized waste oil is then ignited to produce the flame and consequent heat.
There are two known means to force the waste oil through the atomization nozzle. The predominant means is an air driven feed system in which pressurized air is introduced to the flow of waste oil at or near the atomization nozzle, thereby providing the force to push the oil through the aperture of the nozzle. The pressurized air further mixes with the waste oil, thereby creating different patterns of atomization and different flame characteristics, as compared to a system with no air introduced. The second means to force the waste oil through the nozzle is a hydraulic-driven waste oil combustion system wherein the force which pushes the waste oil through the aperture of the atomization nozzle is created by the oil pump pushing the waste oil to the atomization nozzle (see U.S. Pat. No. 4,877,395 issued to Schubach on Oct. 31, 1989).
In the hydraulic-based closed system, on startup, the initial flow of the waste oil causes the waste oil to fill the system piping and thereafter create back pressure based upon the flow. The back pressure is related to the force created by the rate of the flow and dependent, to a limited extent, on the size of the aperture in the atomization nozzle.
The force created by the flow, the closed system, and the size of the aperture in the atomization nozzle, result in waste oil being forced through the aperture and atomized in a given pattern. Systems such as that described in U.S. Pat. No. 4,877,395 issued to Schubach, utilize a needle flow valve (Item 9, FIG. 1, Column 7, lines 60-65, therein to control and regulate the rate of flow through the pipe and between the waste oil pump and the atomization nozzle.
Since there are no applicable, practical limits in the size of the positive displacement pumps typically used, there has likewise not been any practical or other limits on the vertical or horizontal distance the waste oil pump can be located from the atomization nozzle. It has been an industry practice for many years to locate the waste oil pump at the oil tank.
The systems using a positive displacement pump at a constant flow rate have heretofore been unable to sufficiently obtain the optimum efficiency because of their inability to sufficiently control the flow rate. These systems have further not had sufficiently easy or precise adjustability to be efficiently adaptable to oils of different types, weights and other combustion properties.
Existing systems are not indefinitely adjustable to achieve different desired flow rates for fuels of different properties. For instance, when light fuels are used, they typically have a lower energy content per volume and therefore the user receives a reduced heat output for a given volume or flow rate. Further compounding the problems associated with the non-adjustability of other systems is the fact that the flow rates of lighter fuels through the positive displacement pumps is reduced due to gear slippage, thus further reducing the heat output of the heater. Our system's adjustability solves these problems to an extent never before achieved in the art.
In many use situations, the type and combustion properties of the oil used varies greatly and regularly and a fixed, non-adjustable oil pump speed is therefore not the most efficient.
A compound problem occurs when fixed, non-adjustable oil pumps are used with oils of different properties and viscosities, namely: the lighter weight oils produce less heat per given volume and flow rate and their use therefore reduces the heat output of the system; and there is a reduced flow rate of lighter weight oils through the oil pump due to greater gear slippage and other factors. The combination of the lower heat content and actual lower fuel flow rate make the systems currently in use much less efficient and with a substantially lower heat output for lighter fuel oils.
Our invention provides a sufficiently easy and adjustable control means to react to the specific oil being used thereby solving some of the problems associated with other systems. When a different fuel oil is used, the flow rate of the system can easily be increased to maintain relatively constant system heat output by simply adjusting the motor speed and hence the oil pump speed and flow rate generated thereby.
Our invention solves this problem and obtains greater efficiency by greatly increasing the control over the flow rate of the positive displacement pump. Our system uniquely accomplishes this by driving a positive displacement pump with a variable speed motor attached to and controlled by a motor speed control device.
In our system, the burner operator can fine tune and adjust to the optimum flame and efficiency by making adjustments to the motor speed control, thereby changing the speed of the variable speed motor which changes the speed of the positive displacement pump and consequently changing the flow rate of the waste oil.
The flow rate created by the positive displacement pump, in conjunction with the size and shape of the aperture of the atomization nozzle and the air pressure utilized, determines the spray pattern of the waste oil exiting the atomization nozzle and fuel consumption rate in any given system.